DICTIONARY‎ > ‎Geometry‎ > ‎

Triangles

Description: 

Triangle - polygon which has 3 sides , 3 angles and 3 vertices



The sum of the measures of the interior angles of any triangle is 180०



Types of triangles:

1) By the lengths of sides:

Equilateral triangle - has three equal sides and three equal angles.



Isosceles triangle - has minimum two equal sides and minimum two equal angles



Scalene triangle - has no equal sides and no equal angles






2) By the measures of angles:

Acute triangle - has all acute angles




Right triangle - has one right angle and two acute angles





Obtuse triangle - has one obtuse angle and two acute angles





The height is the line from the opposite vertex and perpendicular to the base. Every triangle has 3 heights which intersect in one point.


The height can be outside of the triangle. In the obtuse triangle two heights are outside the triangle.



The area of a triangle is always half the product of the height and base


Area = ½ base × height            P△ = ½ a × h


Author(s):
Mikołaj Dobrzyński

Sources:
http://www.mathwarehouse.com
- notebook for math :-)